It was a Japanese drama, where FL and ML got married when FL was still in high school. It was either an arranged marriage or a forced one. The guy apparently became her teacher.
One of the students had a crush on the guy so she reached his home where the couple tried to hide the fact that they were married. Somehow, she realised that they both were married and in the event, she decided to disclose it. However, the guy himself revealed everything and everyone became emotional.